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FG 80
Reprinted April 2007
$1.50
Winter Wheat in
Summer-Fallow Systems
(Low precipitation zone)
R
L.K. Lutcher, D.A. Horneck, D.J. Wysocki, J.M. Hart, S.E. Petrie, and N.W. Christensen
ecommendations in this fertilizer guide
apply to tillage fallow-winter wheat and
chemical fallow-winter wheat cropping
systems. This guide is one of a set of
publications that address the nutritional requirements of nonirrigated cereal crops in north-central
and eastern Oregon (Table 1).
Recommendations for nitrogen, phosphorus,
potassium, sulfur, chloride, and zinc are covered
in this guide. Soils in the region supply sufficient
amounts of other nutrients for optimum production
of high-quality grain.
Nitrogen
Calculate nitrogen (N) application rates by
subtracting soil test nitrogen from crop demand
for nitrogen. Adjust for excessive straw and/or soil
sampling in the spring of the summer-fallow year.
Evaluate application rates by reviewing the protein
content of harvested grain. A detailed explanation
is provided on pages 2–4.
Growing conditions
Annual precipitation: Less than 12 inches
Soil: Silt loam and very fine sandy loam
Soil organic matter content: 1 to 2 percent
Expected yield
30 to 50 bu/acre
Table 1.—Fertilizer guides for nonirrigated cereal production in low, intermediate, and high precipitation
zones of Oregon.*
Precipitation zone
Publication # Title FG 80 Winter Wheat in Summer-Fallow Systems
Low
FG 81 Winter Wheat and Spring Grains in Continuous Cropping Systems Low
Winter Wheat in Summer-Fallow Systems
Intermediate
FG 82
Winter Wheat in Continuous Cropping Systems
Intermediate
FG 83
Winter Wheat in Continuous Cropping Systems
High
FG 84
*This set of publications replaces FG 54, Winter Wheat, Non-irrigated, Columbia Plateau. Precipitation zones are based on average annual
precipitation and are defined as follows: Low = less than 12 inches; Intermediate = 12 to 18 inches; High = more than 18 inches.
L.K. Lutcher and D.A. Horneck, area Extension agronomists;
D.J. Wysocki and J.M. Hart, Extension soil scientists; S.E. Petrie,
superintendent, Columbia Basin Agricultural Research and Extension Center; and N.W. Christensen, Extension soil scientist, retired;
all of Oregon State University.
Archival copy. For current version, see: https://catalog.extension.oregonstate.edu/fg80
Crop demand for nitrogen
Wheat yield
Table 2.—Grain protein goal and corresponding
nitrogen requirements (per bushel) for wheat.
Grain protein Nitrogen requirement
goal
Average
Range (%)
(lb N/bu)
(lb N/bu)
9
2.2
2.0–2.4
2.4
2.2–2.6
10
11
2.7
2.4–2.9
12
3.0
2.6–3.2
13
3.3
2.8–3.5
Grain protein
maximum yield
Multiply expected yield by the nitrogen requirement to get crop demand for nitrogen. The nitrogen requirement, which is the amount of nitrogen
required to produce 1 bushel of wheat, is based on
a grain protein goal (Table 2).
grain protein
Nitrogen supply
Figure 1.—Generalized relationship of wheat grain
yield and grain protein to nitrogen supply.
Nitrogen requirements for high-protein hard wheat
are greater than those for low-protein soft wheat.
The extra protein in hard wheat accumulates in
grain when plant uptake of nitrogen exceeds that
required for maximum yield (­Figure 1).
Nitrogen requirement
Average nitrogen requirements are suitable for most situations. The ranges given in
Table 2 can be used to compensate for growing conditions or varieties that are genetically
predisposed to having lower or higher grain
protein content.
Subtract soil test nitrogen
Laboratory methods are used to test soil samples
for plant-available nitrogen (soil test nitrogen).
Collect samples from the effective root zone (usually 4 feet) in 1-foot increments and have them analyzed for nitrate nitrogen (­­NO3-N). Samples from
the surface foot also should be analyzed for ammonium nitrogen (NH4-N). Add ­reported values for all
depths to get total soil test nitrogen (Table 3).
A grain protein content of 10 percent is optimum
for soft white wheat. Desired grain protein concentrations for hard wheat range from 11 to 13 percent.
Table 3.—Soil test nitrogen for samples collected in 1-foot increments. Values are used for the ­application
rate calculations on page 3.
Ammonium
Nitrate
Total soil
nitrogen
nitrogen
test nitrogen
Amount to
Soil depth
(NH4-N)
(NO3-N)
(NH4-N + NO3-N)
subtract
(inches)
(lb/acre)
(lb/acre)
(lb/acre)
(lb/acre)
0–12
5
15
20
20
—
15
15
15
13–24
—
10
10
10
25–36
—
5
5
5
37–48
Profile*
5
45
50
50
49–60**
—
12
12
—
61–72**
—
10
10
—
*Calculation of the nitrogen application rate should be based on soil test results from the top 4 feet or the effective root zone.
**Nitrogen in the fifth and sixth foot usually does not contribute to yield, but may increase grain protein.
Winter Wheat, Summer Fallow
Low Precipitation Zone
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Periodic assessment of nitrate concentration in
the fifth and sixth foot can be used to fine-tune
nitrogen management. If nitrate concentrations are
high or increase over time, consider adjusting the
application rate or the time of application. Split
applications may improve nitrogen use efficiency.
Example 3. A nitrogen application rate calculation for hard white winter wheat (13% protein).
Assumptions include:
• Expected yield of 40 bu/acre
• Soil test nitrogen = 50 lb N/acre
• Effective rooting depth of 4 feet
Example 1. A nitrogen application rate calculation for soft white common and club-type winter
wheat (10% protein).
Assumptions include:
• Expected yield of 40 bu/acre
• Soil test nitrogen = 50 lb N/acre
• Effective rooting depth of 4 feet
Crop demand for nitrogen*
(Expected yield) x (per-bushel N requirement)
at desired protein
(40 bu/acre) x (3.3 lb N/bu) @ 13% protein..................... 130
Subtract soil test nitrogen
0–12"............................................................................20
13–24"............................................................................15
25–36"............................................................................10
37–48"..............................................................................5
(lb N/acre)
Crop demand for nitrogen*
(Expected yield) x (per-bushel N requirement)
at desired protein
(40 bu/acre) x (2.4 lb N/bu) @ 10% protein....................... 95
Total soil test nitrogen...................................................50
Nitrogen application rate.............................................80
*
Crop demand for nitrogen rounded to nearest 5 lb.
Subtract soil test nitrogen
0–12"............................................................................20
13–24"............................................................................15
25–36"............................................................................10
37–48"..............................................................................5
Total soil test nitrogen...................................................50
Adjust for excessive straw
Nitrogen “tie-up” in crop residue (immobilization) temporarily reduces the amount of available
nitrogen in the soil; immobilization can be a problem when greater-than-average quantities of straw
are present in the field.
Grain yield can be used to estimate the quantity
of straw. Straw loads increase by about 100 lb/acre
for each bushel increase in yield. Adjust the calculated nitrogen application rate as shown in
Table 4 if grain yield from the previous wheat
crop exceeded the long-term field average by
10 bu/acre or more.
Nitrogen application rate.............................................45
*
Crop demand for nitrogen rounded to nearest 5 lb.
Example 2. A nitrogen application rate calculation for hard red winter wheat (12% protein).
Assumptions include:
• Expected yield of 40 bu/acre
• Soil test nitrogen = 50 lb N/acre
• Effective rooting depth of 4 feet
(lb N/acre)
Crop demand for nitrogen
(Expected yield) x (per-bushel N requirement)
at desired protein
(40 bu/acre) x (3.0 lb N/bu) @ 12% protein..................... 120
Table 4.—Nitrogen application rate adjustments for
wheat yield (straw production) that is greater than
the long-term field average.
Greater-than average
Corresponding
Increase
wheat yield
increase in
application
(previous crop) straw production
rate by
(bu/acre)
(lb/acre)
(lb N/acre)
+10
1,000
10
+20
2,000
20
3,000
30
+30
Subtract soil test nitrogen
0–12"............................................................................20
13–24"............................................................................15
25–36"............................................................................10
37–48"..............................................................................5
Total soil test nitrogen...................................................50
Nitrogen application rate.............................................70
Winter Wheat, Summer Fallow
(lb N/acre)
Low Precipitation Zone
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Adjust for soil sampling (spring of the
summer-fallow year)
Table 5.—Recommended phosphorus fertilizer
­application rates for a range of soil test values.
Amount of
Soil test
Plant-
phosphate
phosphorus (P)
available (P2O5) to apply
(ppm)*
index
(lb/acre)**
20–30
0–5
Very low
Low
10–20
6–10***
0–10
11–15***
Moderate
High
0
Over 15
Decrease the calculated application rate by
10 to 20 lb N/acre if fields are sampled in the
spring of the summer-fallow year. This adjustment
will compensate for mineralization. Mineralization
is a biological process that increases the supply of
available nitrogen in the soil; it is favored by moist
or wet soils and warm temperatures.
Mineralization may increase the supply of available nitrogen by more than 10 or 20 lb/acre when
average or above-average precipitation follows a
prolonged drought. Adjustment of the nitrogen
application rate is not necessary if fields are
sampled within 6 weeks of fall seeding.
*Plant-available index is correlated to sodium bicarbonateextractable phosphorus only and does not apply to other test
­methods.
**Recommended application rates apply to banded or subsurface
shank applications.
***Phosphorus response in fields with soil test values between
6 and 15 ppm is highly variable.
Review protein content
of harvested grain
Phosphorus response in fields with soil test
values of 6 to 15 ppm is highly variable. Yield
increases from fertilization seem to be associated
with: (1) high yield potentials, (2) late seeding
dates, or (3) root diseases that limit plant growth
and development. In fields with soil test levels
between 6 and 15 ppm, effects of fertilization are
best evaluated through on-farm experiments.
Optimum efficiency is achieved by banding
phosphorus. Placement of either liquid or dry
material with the seed, below the seed, or below
and to the side of seed is recommended. Subsurface shank applications also are effective.
Broadcast applications are not recommended.
A postharvest review of grain protein can be a
good way to evaluate application rates. Higherthan-desired protein indicates overfertilization—
if growing conditions were normal or about average. High protein also can be caused by unusually
dry conditions or nitrogen that is positioned deep
in the soil profile.
Lower-than-desired protein may be due to an
insufficient application rate. Low protein also can
be a problem when late-season rainfall results in
above-average yield or when nitrogen losses occur
during or after application. Examples of nitrogen
losses include “escape” of anhydrous ammonia
from dry soil or an unsealed soil surface, volatilization of surface-applied urea, and nitrate leaching below the root zone.
Soil sampling for phosphorus
Collect soil samples for phosphorus testing from the surface foot. Reported values are
best thought of as an index of availability. The
test cannot be used to calculate the pounds of
plant-available P2O5 per acre.
Phosphorus
Application of 20 to 30 lb P2O5/acre should
increase yield if soil test phosphorus (P) levels are
5 ppm or less (Table 5). A phosphorus application is not recommended when soil test values are
greater than 15 ppm.
Winter Wheat, Summer Fallow
Low Precipitation Zone
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Potassium
Table 6.—Plant-available sulfate-sulfur and
­recommended fertilizer application rates for a
range of soil test values. Soil test
Amount
sulfate-sulfur
Plant-
of sulfur (S)
(SO4-S)
available
to apply
(ppm)
index
(lb/acre)*
0–5
Low
10–15
6–10
Moderate
10
High
0
Over 10
Soil potassium (K) concentrations in the
region generally are high or very high (>100 ppm
extractable K). Fertilizer applications are not
­recommended.
Sulfur
Sulfur (S) is one of the most limiting nutrients
for wheat production—second only to nitrogen in
importance. The sulfur requirement of the wheat
plant is about one-tenth the nitrogen requirement.
Sulfur is necessary for optimum yield and highquality baking flour.
Sulfur deficiencies in wheat are fairly common
in the spring after a wet winter. Above-average
precipitation moves sulfate-sulfur (SO4-S), the
form of sulfur available to plants, below the root
zone. Deficiency symptoms often disappear later
in the season as root growth extends to deeper layers of the soil profile.
The soil sulfur (SO4-S) test is not definitive.
Low or moderate soil test levels (Table 6) are
a first indication that fertilization might be
­warranted. Other factors need to be considered.
Yield responses are more likely if one or more of
the following situations apply: (1) winter wheat is
seeded late in the fall, (2) more than 5 years have
passed since the last application of sulfur, and/or
(3) greater-than-average quantities of straw are
present in the field. Field experience, observation,
and on-farm experimentation provide valuable
information about the need for sulfur.
*A decision to apply sulfur should not be based on soil test results
alone. Sulfur may be beneficial if SO4-S soil test values are low
or moderate and if: (1) winter wheat is seeded late in the fall,
(2) more than 5 years have passed since the last application of
sulfur, and/or (3) greater-than-average quantities of straw are present in the field.
Optimum efficiency is achieved by banding sulfur. Placement of either liquid or dry material with
the seed, below the seed, or below and to the side
of seed is recommended. Subsurface shank applications also are effective.
Ammonium thiosulfate liquid (Thiosul,
12-0-0-26) is an effective source of sulfur, but it
can injure or kill seedlings when placed with the
seed. Avoid this problem by placing the product
below or below and to the side of seed.
Elemental sulfur should be used with caution
because it is not immediately plant-available.
Microorganisms oxidize elemental sulfur to plantavailable sulfate, but conversion occurs slowly and
is regulated by the moisture status and temperature
of the soil. Most of the elemental sulfur will not be
available until 2 or 3 years after application. Rates
of 100 lb elemental S/acre may be necessary to
ensure that adequate sulfate is available during the
first growing season.
Soil sampling for sulfur
Collect soil samples for sulfur (SO4-S)
testing from the surface foot. The test is not
definitive, and reported values are best thought
of as an index of availability. Field experience,
observation, and on-farm experimentation
provide valuable information about the need
for sulfur.
Winter Wheat, Summer Fallow
Chloride
Research shows that application of chloride (Cl)
may increase grain yield, test weight, and/or kernel
size. It is important to note, however, that these
responses occur only some of the time.
Chloride applications are known to increase
yield of winter wheat suffering from “Take-all”
Low Precipitation Zone
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root rot, and they reduce the severity of physiological leaf spot. Yield responses in the absence
of disease also have been observed and may be a
consequence of improved plant–water relations.
Consider applying chloride if soil test concentrations in the surface foot are less than 10 ppm.
The recommended application rate for chloride is
10 to 30 lb/acre. Benefits from fertilization may
last for several years.
Yield increases, when they occur, usually range
from 2 to 5 bu/acre. Responses are most often
associated with above-average yield. Growers
are advised to experiment with chloride on small
­acreages.
Do not apply chloride with the seed; it is a
soluble salt that can delay germination or injure
or kill germinating seeds. Rain is required after
Winter Wheat, Summer Fallow
a­ pplication to move surface-broadcast chloride
into the root zone.
Potassium chloride (KCl) is the most readily
available source of chloride.
Zinc
Zinc (Zn) fertilization of dryland wheat has
not been economical in research trials. On-farm
experiments with fertilization should be limited to
small acreages. A zinc application rate of 5 lb/acre
is appropriate. A 10 lb/acre application should last
for several years.
The potential for a grain yield response
increases when DTPA-extractable soil test zinc
values (surface foot) are less than 0.3 ppm, soil
phosphorus levels are moderate to high, the soil
pH is greater than 7.5, and yield potential exceeds
50 bu/acre.
Low Precipitation Zone
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Soil Test Interpretation Guide, EC 1478.
Nibler, F.J. Fertilizer Requirements of Wheat
Grown Under Conservation Tillage. M.S.
­Thesis, Oregon State University, 1986.
Petrie, S.E., P.M. Hayes, N.W. Blake, A.E. Corey,
K.E. Rhinhart, and K.G. Campbell. 2004. Chloride Fertilization Increased Winter Wheat and
Barley Yield in Northeastern Oregon.
In: Columbia Basin Agricultural Research
Center Annual Report, 2004. Oregon State
University.
Pumphrey, F.V. and P.E. Rasmussen. 1982. Winter
Wheat Fertilization in the Northeast Intermountain Region of Oregon, CI 691 (Oregon State
University).
Rasmussen P.E. and P.O. Kresge. 1986. Plant
­Response to Sulfur in the Western United
States. In: Sulfur in Agriculture. M.A. Tabatabai
(ed.). Agronomy Monograph (27). ASA-CSSASSSA. Madison, WI.
Stoskopf, N.C. 1985. Cereal Grain Crops. Reston,
For more information
*Brown, B.D., M.J. Westcott, N.W. Christensen,
W.L. Pan, and J.C. Stark. 2005. Nitrogen Management for Hard Wheat Protein Enhancement,
PNW 578.
Christensen, N.W., R.G. Taylor, T.L. Jackson, and
B.L. Mitchell. Chloride Effects on Water Potentials and Yield of Winter Wheat Infected with
Take-all Root Rot. Agron. J. 73:1053–1058.
Cook, R.J. and R.J. Veseth. 1991. Wheat Health
Management. The American Phytopathological
Society, St. Paul, MN, APS Press.
*Douglas, C.L., D.J. Wysocki, J.F. Zuzel,
R.W. Rickman, and B.L. Klepper. 1990. Agronomic Zones for the Dryland Pacific Northwest,
PNW 354.
*Hart, J.M. 2002. Analytical Laboratories Serving Oregon: Soil, Water, Plant Tissue, and Feed
Analysis, EM 8677.
*Marx, E.S., J.M. Hart, and R.G. Stevens. 1999.
*Oregon State University and Pacific Northwest Extension publications
Many OSU and PNW Extension publications, including the publications in this set of fertilizer
guides, may be viewed or downloaded from the Web. Visit the online Publications and Videos catalog
at http://extension.oregonstate.edu/catalog/
Copies of many of our publications and videos also are available from OSU Extension and Experiment ­Station Communications. For prices and ordering information, visit our online catalog or contact
us by fax (541-737-0817), e-mail (puborders@oregonstate.edu), or phone (541-737-2513).
Winter Wheat, Summer Fallow
Low Precipitation Zone
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© 2006 Oregon State University.
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Revised November 2006. Reprinted April 2007.